Centrifugal clutch



Nav. 22, .1949 M. MER-z GENTRIFUGAL CLUTCH 'Y Filed March 24, 1945 VWM , 0 m mm 4 X Y. an

Patented Nov. 22, 1949 UNITED STATES PATENT OFFICE CENTRIFU GAL CLUTCH Max Merz, Seattle, Wash.

Application March 24, 1945, Serial No. 584,558

3 Claims.

This invention relates to clutches, and it has reference more particularly to an improved type of automatic clutch applicable to various uses, but especially designed for use in the driving mechanism of timber saws; it being the principal object of the invention to provide a clutch mechanism, adapted to be interposed in the driving mechanism between the engine drive shaft and the saw driving gear, comprising a driven clutch head which, incident to its rotation and under the influence of centrifugal force, is caused to functionally engage a clutch drum, and wherein the driving connection or contact between driving and driven parts of the clutch become ineffective at a slow speed or at what might be called stalling speed so that the clutch becomes automatically disengaged under this condition.

More specifically stated, the invention resides in the provision of an automatic clutch designed for use in the driving mechanism of power saws and whereby the clutch becomes disengaged when the saw becomes stuck or pinched for any particular reason, and thereby prevents stalling the engine, and damage to saw or engine mechanism.

Still further objects of the present invention reside in the details of construction of parts embodied in the clutch, in their relationship and mode of operation, as will hereinafter be fully described.

In accomplishing these and other objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is an enlarged, sectional view of the clutch mechanism in an axial plane.

Fig. 2 is a cross section on line 2--2 in Fig. 1.

Fig. 3 is a cross section on line 3-3 in Fig. 1.

Fig. 4 is a face view of one of the clutch shoes.

Referring more in detail to the drawings:

In Fig. 1, 25 designates an engine driven shaft and 20 designates a shaft that is coaxially aligned therewith and which may be driven, through the mediacy of the present clutch mechanism, to drive a saw or other device used therewith. This clutch mechanism will now be described.

The clutch comprises a part which will be hereinafter referred to as the clutch head, and a part which will be referred to as the clutch drum. The head rotates with the engine drive shaft and it comprises a plurality of arcuate segments that are caused to be pressed by centrifugal force against the drum to effect the driving of the latter, which, in turn, drives the saw. The clutch head is desighated in its entirety by reference numeral 35.

The engine drive shaft 25 has its outer end portion contained within the hub portion 30' of the clutch head and, as noted best in Fig. 1, the shaft has an end portion of reduced diameter` that is keyed, as at 3|, in the said hub and the head is held in place on the shaft end, against endwise movement, by a bolt 32 that is applied through a washer 33 and threaded into the shaft end; the washer being seated against a shoulder 34 that is formed by a counterbore in the hub.

The hub 30' is formed about one end with two spaced, annular flanges 35 `and 36 setting olf an intermediate channel 31 in which the three segmental shoes 38--38-38 of the clutch head are contained for radial movement. Each segment 38 of the clutch head extends through an arc of approximately 120, and as shown best in Fig. 4, has a cylindrically curved flange 38a, and these nanges are adapted to cooperatively engage with the inside surface of the cylindrical flange 39 ofl the clutch drum 40 which is fixed on the inner end of the transmission shaft 20.

Formed on thev side face of each shoe or seg-v ment of the clutch head, is a projecting lug 4I, and these lugs are slidably fitted in radially directed slots 42 in the flange 35, thus allowing the arcuate outer surfaces of the segments to be moved into and from frictional driving contact, with the drum ange while maintaining theiry driven connection with the hub member.

Interposed between the shoes or segments are coiled springs 45 designed to urge the shoes yield,- ingly apart and into driving contact with the drum flange under slight pressure. These springs are seated at their opposite ends in sockets 46. in the adjacent radial surfaces of the shoes.

In order that the shoes may be held entirely disengaged from the drum ange, when such is desired, I have applied a sleeve 58 about the hub portion 30 of the clutch head. This sleeve is slidably adjustable on the hub, in its longitudinal direction, and at its inner end it has an encircling, conically tapering cam surface that cooperatively underlies the inner end portions of the inwardly directed arms 51a of three bell crank levers 5l which are pivotally mounted on pivot pins 52 carried by paired ears 53 formed on the inner face of the flange 36. The outer arms 5Ib of the three levers extend through slots 55 in the ange 35 and into sockets 55 in the adjacent side surfaces of the shoes, respectively. The arrangement of parts is such that when the sleeve is fitted inwardly, that is, toward the engine, the cam surface 50 engages the arms 5Ia of the bellcranks and rocks them, to cause the arms 5Ib to 3 move the shoes inwardly toward the axis of rotation and thus to be held disengaged from the drum.

For the purpose of shifting the sleeve, I have applied a collar 60 thereto, carried by anti-fric- 5 tion bearings 6l. The collar has radially eX- tending trunnions 60 at opposite sides and these are pivoted in the opposite side arms 62-62 of a bifurcated lever 63 which arms are pivoted at their ends'to thehousing The other end, ofgthe lever has'a flexible'rod or shaftlconnection 65T with an adjusting grip member 66 at the end of a handle l1; the connection being such thanV rotation of the grip shifts it lengthwisel either handle, and this in turn, through the lcable 65.' 15 rocks the lever and shifts the sleeve, ei ther,to,; disengage the shoes or to releasethern fore v ment with the drum. f

With the parts so constructed and assembieg, it is quite apparent that with the shoes released foncontact, with the vdrum harige, centriiugal id icefwfil causethein to'jbe firmly piess'ediito holding contact with' the drumj flang'efand the;` h'ih'efrthe rate'of"rotation,"the "greater will el'v jy ldi'ngiand driving ei'iect on the drum. How'fj e @Mirthe slawshquid bine i stick, nii-is will' slqw the;'speed'of the engine to an extentth'aft c'n fiugial'iorein the clutch head will notholld. tlil drivingl'ic'onnectionbetween shoes and clrurlii,"` andtiiebiutchfwill slip to an extent to prevent' thestalling of the engine- ""H iri'gthus 'described my invention, what I i, as 'newtherein and desire to secure byy Leut-l' ie.; garantis.; i ""l n'ti combination, a driving shaft, a driven shafrtalin'ed therewith, and a clutch; said clutch cmprising a clutch head having a hub p tuirtioii ie'lj'onthedriving shaft and having spacedan'f` nular narigs thereabout and there beigrad'il slots'inneof said flanges,V4 a drum mounted on th'edriven'shaft and coaxially enclosing theh'ea'd'," clutch `shosarranged about the head between" said flanges and having 'lugs thereon 'guidedfin" tljieadial' slot s"of one flange effecting a driving connection' Between' the'shoes and head, and"y 45 yielding 'means acting against the Vshoes tofui uiejifitouriving contati` with the drum. 2.In combination', a'driving shaft, 'a 'd riven shaft alined therewith and a 'clutchj s 'aid cllitcl"l comp'risi'r'ig clutch head having 'a' hub prtiiij' xed lon the driving shaft and'having 'spelledY` annularanges thereabout and there being radial slt's'in'nn'e'f said flanges, a drum mountedijcir the" driven shaft and coaxially enclosing the hea'd," clutch'sh'oes 'arrangedfabout theA head between said"a`nges'an'd having lugs thereon guidei-,l

the said radial slots and effecting a driving connection between the shoes and head, yielding means acting on the shoes to normally retain them in driving contact with the drum, bell crank levers mounted on the head, each with a lever arm engaged with a shoe, a cam sleeve longitudinally slidable on the hub portion of the head and engageable with the other lever arms of the bell crank levers to move the shoes from driving contact with the drum, and means for shifting the sleeve.

3. In combination, a driving shaft, a driven shaft aligned therewith, and a clutch; said clutch comprising a clutch head having a hub portion Xd onithe driving shaft and having spaced annular flanges thereabout at one end of the hub,

and therebeing radial slots in said flanges, a cani sleeve's'lidable'on the other end portion of the hub, a drum mounted on the driven shaft and coaxially enclosing the head, clutch shoes arranged about the headbetweenthe spaced flanges and having lugs thereon guided in the rac'lialslots of that ange that is farthest' from the cam"` sleeve and effecting a driving connection between the shoes and head, springs interposed between the shoes andl acting thereontourge them with limited force into driving Contact with the drum, bell crank levers pivotally mounted on the flange that is nearest the cam sleeve, having arnis'ex'-` tended through the Vvradial slots of said flange into actuating contactV with said shoes, and having their other arms simultaneously engageable by the cam sleeve for moving the shoesout'of contact with the drum, and means foi-'shifting the said cam sleeve to 'engage or 'disengage' the shoes and drum.

MAX MERZ.

REFERENCES ACITED The following references are of record in the le of this patent:

Number Name DateA 1,045,480 Wallmann Nov. 26,1912 1,227,475 Matheeuwissen May 22, 1917 1,597,326 Mercer Aug. 24, 1926l 1,715,351 Bruckmann Junefi, 192.9` 1,910,352 Moyer May 23, 1933 2,027,941 Waterhouse Jan. 14, 1936 2,077,292 Waseige Apr.,13, 1937 FOREIGN PATENTS Number Country Date 582,131 Germany Aug. 9,1933 

